1) I define medieval era by existence of feudalism and similar systems where economy is based on personally free but land-locked peasants - so Roman coloni, Ottoman timariot system, European feudalism, Byzantine thematic system. Basically, you do not have slavery, but you do not have urban industrial society either. 2) Personally, I live in Croatia. When it comes to my setting, it is based on variety of inspirations (9th century Roman Empire, 15th century Hungary-Croatia and Holy Roman Empire, 15th century Poland, 15th century Ottoman Empire etc.).